The five year program of mentored research and training outlined in this proposal is designed to develop Dr. Brookhart, a biostatistician, into an independent investigator working at the intersection of geriatrics, biostatistics, and drug epidemiology. The primary research aim of this proposal is the development and application of hierarchical statistical models for the study of complex patterns of prescription drug use by the elderly, an area of great clinical and policy importance. The data that are available to understand medication use have a multilevel structure consisting of repeated observations on patients who cluster within physicians, practices, and geographic regions. To capture the complex structure of the data and answer important substantive questions about prescription drug use by older patients, we propose to employ modern statistical approaches for the analysis of hierarchical data. With increasing concern over the appropriate use and cost of prescription drugs, particularly with the new Medicare drug benefit, such models of prescribing and adherence can play an important role in improving the use of medications. By understanding common patterns of prescription medication use, targeted and cost-effective quality improvement intervention can be designed. In the final phase of this award the candidate will develop multilevel statistical approaches for creating patient, physician, practice, and region profiles that can be used to target quality improvement interventions that aim to promote more appropriate prescribing and higher levels of patient adherence to effective therapies. Different profiling approaches will be pilot tested and compared as part of a future R01 proposal. The mentored research outlined in this proposal will be complemented by a formal training program that will involve coursework in gerontology, geriatrics, chronic disease epidemiology, theories of health behavior, prescription drug and health care policy, and health services research;regular meetings with mentors and other senior faculty;attendance at seminars, workshops, and academic conferences;and systematic exposure to clinical geriatrics including time spent in outpatient, inpatient, and long-term care environments.